Hey there, my name is Greta Shum, and I'm writing to you from a ship in the Southern Ocean! I'll tell you about my adventures aboard this research vessel as well as the science. Learn more about my project in particular, at soccom.princeton.edu.

Wednesday, December 28, 2016

Let's Get Started!

We’re underway!

At 0700 on Christmas Eve, the N.B. Palmer set sail from the dock at Punta Arenas and sailed north. The plan was to pick up some large containers of hazardous materials, tie them on to the ship and then turn around, and sail west through the Strait.

The N. B. Palmer steams ahead through the Strait of Magellan toward the Drake Passage!

Now that we’re through, we’ve reached water deep enough to deploy our first float. (Yay!) The first one, RE Byrd, was deployed in the morning on December 27th at 10:00. The second, RF Scott, was deployed at 0300 on December 28th. It was a long day if you didn’t take a nap.

Here, RF Scott (named by the Princeton Day School) is deployed at 0300 on December 28th.

The first two floats (of 12 total) were be deployed using a new technique. It goes like this: the float is held in what looks like a cardboard box. It's purpose is to keep the float safe during deployment. The sides of the box are held together by a special kind of tape. In theory, within about 15 seconds of this tape being exposed to water, it will release its seal and the box will come apart, releasing the float to the open water.

As the float drifted away, we waited for the box to fall apart, but we lost track of it within minutes. Later we heard that RE Byrd, the first float deployed, was talking successfully to the satellites. He had escaped his box! Keep your fingers crossed that RF Scott escapes as well!

Stephen Riser maps out the N. B. Palmer's trajectory over the course of the cruise.

If you remember, Steve Riser is the man whose lab, up at the University of Washington, made these floats. When he describes them, it’s almost as if he’s describing not one thing but many because there are so many things going on at once! And in fact, he is. On top of the float sit an array of sensors. Each must be durable enough to take precise measurements in severely cold and deep water. The water at a depth of 2000 meters is critically different than the water at surface level. The float must give reliable information across the different levels of pressure.

Quick question: Can you figure out what the pressure would be on the float at a depth of 2000 meters? (Hint: Pressure increases about one atmosphere for every 10 meters of depth.)

What are the sensors measuring? Among other things: temperature, pressure, salinity, oxygen content, nitrate content, chlorophyll, and pH.

But wait, no carbon sensor? Isn’t the purpose of this project to measure carbon in the Southern Ocean?

Yes it is! And the scientists are actually doing that, just in a scientist’s way. For example, a scientist might not ask, “how long until lunch?” Instead, she might ask, “what time is it?”, “what kind of food is the chef preparing?”, “how long does that take to prepare?”, “how far away is the dining area?” And then once all those questions are answered, the scientist will sneak way and calculate the exact lunch situation!

That’s kind of what’s going on with the floats. Instead of directly measuring carbon in the ocean—which takes many different forms, from organic life to carbonic acid—SOCCOM scientists are measuring oxygen, nitrate, and pH at different depths in order to infer the carbon situation at that depth from these other quantities.

It’s important to note also, the floats don’t directly measure depth; instead they measure pressure! That will give you depth, as you've shown above.

All of the sensors on the float are affected by the water's temperature and salinity. In order for those other sensors to provide data that scientists can use, the temperature and salinity sensors need to be working! In addition, the float’s ability to control where it is in the water column depends upon the pressure sensor working correctly—to know where it is! If the pressure sensor stops working, we’re up a creek—er rather, Southern Ocean!

The poor sensor! That's a lot of pressure, am I right?! ;)

Tomorrow, December 29th at 1300 Eastern, all of the leading scientists on this ship will gather and answer questions on a Reddit AMA (Ask Me Anything, or in this case, Ask US Anything!). Tune in to follow along! I’ll be updating this blog with a link to the post!